It is a requirement in cable- and pipe laying, and civil engineering in general, to compact soil in a trench, or other confined space, to return the soil to its original grade. For reasons of cost, safety and consistency of results, it is normal to fit a rotatable wheel or drum to a suitable earthmoving machine, the wheel or drum being rolled back and forth over the soil area to be compacted until a suitable level of compaction is obtained.
FIG. 1 shows one such arrangement. A wheel-type compacting device 1 is mounted to a backhoe excavator 2 in place of the usual bucket. The device 1 is able to rotate freely about an axis 3 that is parallel to the axes 4 and 5 about which the backhoe's dipper (sometimes alternatively called stick) 6 and boom 7 rotate. The backhoe operator positions excavator 2 so that axes 4 and 5 are perpendicular to the length of a trench 8. The operator can then readily position the device 1 at the base of the trench, and by operation of boom 7 and stick 6, roll the device backwards and forwards along the trench to compact the soil therein. The device 1 is typically provided with radially projecting feet 9 to enhance the compaction effect but may also take the form of a plain-surfaced wheel or drum.
In some circumstances vibration devices may be employed with the device 1 for better compaction, and sometimes no vibration capability is provided, reliance being placed simply on repetitive pressing downward of the soil surface by the feet of the wheel.
Other types of machines may be used for mounting the compacting devices such as device 1. For example, device 1 may be mounted to other types of excavators, such as telescopic-boom excavators (sold by Gradall Inc., USA), and to the boom-and-stick backhoe arrangements that are often fitted to the rear of wheeled loaders. With suitable adaptors, front-end loaders of the articulated or skid steer type may also be fitted with compacting devices.
Compacting devices that comprise a single drum with feet projecting therefrom and which is supported for rotation between fork arms can lead to difficulties in compacting soil adjacent the walls of a trench. This may be due to the fact that the fork arms are of a size that can prevent the drum accessing the soil at the perimeter of the trench, adjacent the longitudinal walls of the trench. It is therefore known to provide compacting devices, such as device 1, that employ several individual wheel disks 10 on a common shaft, with supporting members 11 arranged therebetween. In the arrangement as shown in FIG. 1, supporting members 11 are secured to a structure 12 releasably attached to the stick 6 and provide support for an axle (not shown) on which are mounted the wheel disks 10.
However, devices of this type, have their own problems. Gaps are needed between some wheel disks 10 to provide clearance for the support members 11 and the ground below such gaps receives no significant compaction. Therefore, to provide adequate and even compaction over the whole width of a trench floor, it may be necessary to shift the device 1 laterally one or more times to ensure that all the soil within the trench is compacted. This can be a time consuming process that requires significant operator skill in manoeuvring the machine.
Therefore, there is a need to provide a compacting device that provides improved soil compaction in a relatively simple manner.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.